ReviewThe Heartbeat Of Japan: The Grand Seiko Kodo Constant-Force Tourbillon SLGT003
Grand Seiko’s first mechanical complication watch, the Kodo Constant-Force Tourbillon, marks a breakthrough in watchmaking by merging a tourbillon and a constant-force mechanism into a single axis for enhanced stability and precision
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Anyone who knows anything about watches understands how unique Grand Seiko is. The brand is renowned for its exceptional craftsmanship, accessibility, and devotion to accuracy. This extends from their legendary spring drive movements to their high-end quartz movements and everyone’s favourite 9S range. However, one thing that has been missing from their collection is a mechanical complication—until now. The Kodo Tourbillon is Grand Seiko’s first-ever tourbillon wristwatch, the brand’s first constant force mechanism, and the first movement in the world to combine the two escapement concepts into a single element. This is a game-changer for the brand and has fans, including me, excited for what’s to come.
Kodo In Constant Rhythm
It was back in 2020 when Grand Seiko made headlines with the announcement of its T0 concept tourbillon movement. Developed over a period of five years of research and development by engineers and watchmakers, led by Takuma Kawauchiya, the T0 combined a tourbillon with a remontoir constant-force mechanism. A remontoir is a small spring that acts as an intermediate source of power between the mainspring and the escapement, providing a consistent supply of energy to the escapement over a longer period of time.
The combination of a remontoir and a tourbillon allowed Kawauchiya’s constant-force tourbillon to address two of the major factors that affect chronometry in mechanical watches—positional errors and variations in energy supply. While tourbillons have become increasingly common in recent years, constant-force mechanisms remain a rarity, making the T0 a truly unique and innovative addition to the world of watchmaking.
True to Grand Seiko’s standards, the Kodo is a standout in the world of high-end watches. Kodo, which means ‘heartbeat’ in Japanese, is named after the rhythmic motion and sound made by its two mechanisms. The inner tourbillon carriage rotates seamlessly as the balance vibrates steadily at eight beats per second, and the outer constant-force carriage follows its rotation at exact one-second intervals, creating a precise rhythm that resembles a musical 16th note or semiquaver. The watch’s unique sound is made possible by the 9ST1 movement, which has the highest frequency ever to incorporate a constant-force mechanism. With a total of 340 components and 44 jewels, this manual movement ticks away at a rapid pace of 28,800 vibrations per hour, ensuring unmatched accuracy with a maximum deviation of just +5 to -3 seconds per day. And with a hefty 72-hour power reserve, the company has made sure that the timepiece is more than just a pretty face.
The Samurai Style Of Kodo
The Grand Seiko Kodo Constant-Force Tourbillon has a skeletonised dial that is similar to the T0 concept, but has been redesigned for improved functionality, and to reflect Grand Seiko’s aesthetic. The main timekeeping subdial at 12 o’clock showcases the brand’s signature bevelled dauphine hands and applied baton indices on a skeletonised chapter ring, offering a glimpse into the movement’s gear train and mainspring barrel. The power reserve indicator at eight o’clock has also been updated with a Grand Seiko-style layout and a bevelled dauphine hand.
The 43.8mm case of this timepiece boasts a unique combination of platinum 950 and Brilliant Hard Titanium, showcasing Grand Seiko’s signature hand-finishings with mirror-polished and hairline accents. Despite its intricate openworked design, the watch is still water-resistant up to 100m. The watch comes with a black calfskin strap that is hand-painted with Urushi lacquer, similar to the technique used for Samurai armour. The strap is secured with a platinum triple-folding clasp, and a crocodile leather strap is also included.
The Grand Seiko Kodo Tourbillon is a truly remarkable timepiece that represents the best of Japanese watchmaking. With its stunning design and impressive movement, this watch delivers truly world-class haute horlogerie spectacle with a refined Japanese style. With only 20 of these spectacles being made, this watch is simply a must-have for any serious collector.
